Field of the Invention
The present invention relates generally to an alarm for detecting the unauthorized opening of a sliding door or window, and more particularly to an improved lightweight, portable, wireless electronic alarm device which may be easily installed horizontally or vertically in the casing of a sliding door or window to resist forced opening of the sliding door or window while simultaneously sounding a highly audible alarm signal indicative of an attempt to break in.
One of the consequences of our increasingly crowded urban society has been the inexorably increasing crime rate, the mere threat of which has driven many people to be security-conscious. Breaking and entering and burglary have become increasingly common occurrences, particularly in the case of residential property. Accordingly, the sale and installation of various security systems such as burglar alarms has become a thriving business as many property owners seek to discourage crime to property through the use of such systems.
There are two basic types of security systems: first, the professionally-installed central security system, which is used in privately-owned houses and luxury apartments, and secondly the owner-installable or portable systems of various types which are each installed on a single door or window. The second type of device is particularly used by apartment dwellers, both since the purchase of such systems are more economical, and since they can usually be removed and taken when the owner of the device moves. They also find substantial use in homes of people who do not wish to pay the high price of a central security system.
In most apartments and homes the windows are sliding windows, either opening by sliding the moveable window horizontally or vertically to open or close them. Some apartments and homes have exterior patios with sliding doors, which slide horizontally to open or close. A number of the relatively inexpensive, owner-installable security devices, unfortunately, do not work with such slidable doors and windows. Typical of one type of such systems are those shown in U.S. Pat. No. 2,870,281, to Mitchell, in U.S. Pat. No. 4,442,427, to Morton, and in U.S. Pat. No. 4,607,253, to Wooten, et al. These devices are intended for use with a conventional hinged door which opens inwardly, and act as braces installed with one end under the doorknob and the other end on the floor away from the door. When the door is opened slightly, these devices will inhibit the door from opening and will provide an audible alarm.
The other type of device is illustrated by U.S. Pat. No. 4,540,980, to Porco. The Porco device is illustrative of those devices which are placed in front of an inwardly opening hinged door. When the door is opened, the device will be jarred or tipped over, causing an alarm to be sounded. Other similar devices are designed to be hung from the doorknob, and will react to the door being opened through the use of motion detectors. Unfortunately, neither the devices installed as braces under the doorknobs or the devices which are tipped over or jarred by the door being opened are useable on sliding doors or windows.
Accordingly, it is the primary objective of the present invention to provide an alarm device which is useable on sliding doors and windows. The most popular type of device useable on sliding windows and doors is the bar-type device, which is illustrated in U.S Pat. No. 4,193,067 to Hawkins in U.S. Pat. No. 4,495,486, to White, and in U.S. Pat. No. 4,553,134, to Holt. The Hawkins device has a rod which operates a mechanical switch, with a detent retaining the rod in a position to continuously operate the switch once initially operated. The White alarm acts as a physical obstruction preventing opening of a sliding door or window until it is removed, at which time the alarm will be sounded.
The Holt device is a spring-loaded bar which may be installed in a window casing. The Holt device has a significant disadvantage that it is not widely adaptable to different size window casings. While the spring allows a small degree of adjustment, it is not sufficiently wide to allow the Holt device to be installed in windows of more widely varying widths. It is thus desirable that the alarm device of the present invention be adjustable to fit in a more widely variable group of window or door sizes.
While sliding doors and many sliding windows open and close horizontally, a substantial percentage of sliding windows open and close vertically rather than horizontally. It is accordingly desirable that the present invention provide a design for an alarm which will be universal in its ability to fit into vertically opening and closing windows as well as horizontally closing doors and windows.
It is also an objective of the alarm device of the present invention that it be both simple and easy to install. No tools should be required in the installation, and installing the device should not result in any damage to the door, the window, or the casing in which the door or window is mounted. It is a particular disadvantage of highly visible devices that they are not aesthetically pleasing. As a result, highly visible devices will not be desirable to a large number of prospective buyers even though the visibility may have some effect to discourage intruders. Therefore, the alarm device of the present invention should be unobtrusive when installed so as not to effect a disconcerting presence inside the property.
It is also apparent to those skilled in the art that by making the alarm device of the present invention portable as well as easy to install without requiring tools, it is also made highly desirable for use by travelers in windows in hotel rooms. In addition, of course, it is desirable that the improved alarm device of the present invention be mechanically simple to ensure reliable operation. Therefore, as few moving parts as possible should be utilized, to enhance the reliability of the device. The operation of the device should sound an alarm when a forced entry is attempted. Note that the White device mentioned above does not operate in this manner, but rather sounds an alarm only when removed.
In addition, the improved alarm device of the present invention should also be of solid state construction, to ensure a long, reliable lifetime as well as energy efficient operation. When the alarm is sounded, it should continue until the device is reset, with the resetting operation being simple yet not obvious upon initial inspection. The alarm of the present invention should also be of inexpensive construction, thereby ensuring the broadest possible appeal in the alarm market. Finally, the improved alarm of the present invention should provide all of the aforesaid advantages and objectives without incurring any relative disadvantage.